* diagnostic.h: #include location.h
	(location_t): Move definition to..
	* location.h: ... here.  New file.
	* tree.h: #include location.h
	(DECL_SOURCE_LOCATION): New macro.
	(DECL_SOURCE_FILE): Use.
	(DECL_SOURCE_LINE): Likewise.
	(struct tree_decl): REplace filename and linenum with locus.
	* Makefile.in (TREE_H): add location.h
	(diagnostic.o): Depends on gt-location.h
	(gt-location.h): Depends on s-gtype

From-SVN: r55364